Ink jet recording sheet

ABSTRACT

An ink jet recording sheet comprising a paper support applied on at least one surface thereof or internally with a composition which comprises an aqueous dispersion of polyvinylpyrrolidone, vinylpyrrolidone-vinyl acetate copolymer or a mixture thereof serving as a binder or sizing agent and a white filler. The white filler is contained in a weight ratio, to the binder, of 10:1 to 0.2:1 when the composition is applied on the surface of the paper support. When the composition is internally incorporated in the recording sheet, it comprises 10 to 60 parts by weight of the filler and 2 to 20 parts by weight of the binder per 100 parts by weight of pulp.

This is a division of application Ser. No. 294,152 filed Aug. 19, 1981,now U.S. Pat. No. 4,425,405.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to ink jet recording and more particularly, torecording papers for the ink jet recording.

2. Description of the Prior Art

Great interest has recently been attracted to the recording by ink jetsystems because of their reduced noise, ease in color recording,possibility of high speed recording, and utilization or ordinary papers.The ink jet systems are now being used widely in the field of facsimile,various types of printers and the like. It is generally accepted thatordinary papers are satisfactorily usable as recording paper for use inthe ink jet recording system. However, this does not mean that all theordinary papers which are widely used at present are usable. In order toobtain recorded matters of more excellent quality, the recording paperitself should meet several requirements which follow: (1) The paper musthave excellent ink receptivity to allow ink dots deposited on the papersurface to be rapidly absorbed in the inside of paper; and (2) The papermust prevent ink dots applied on the surface from running or spreading.

The requirement (1) is the most fundamental one which must be furnishedwith ink jet recording papers and assumes great importance especiallywhen color images are produced by the ink jet system. This is because inorder to produce color images, it is necessary to make a variety ofcolors from combinations of yellow, cyan and magenta inks, so that inksof different colors are deposited on the same portion of the papersurface, resulting in large amounts of inks per unit area.

The requirement (2) is necessary for obtaining clear recorded matters.By preventing ink dots from spreading, the optical density of recordedmatter can be increased. In general, the simplest method of increasingthe optical density of recorded matter is to increase the concentrationof dye in the ink. However, this method has its limit because of thetendency to clog a head nozzle. Accordingly, it is important thatrecording papers satisfy the above requirement.

Aside from the fundamental requirements (1) and (2), recording papersshould satisfy the following further requirements: (3) The degree ofpenetration of ink in the direction of depth or in the longitudinaldirection is not too great; and (4) The paper has an excellentbrightness. The optical density of recorded matter largely depends onthe state of the paper surface and if the degree of the penetration inthe direction of depth is too great, it is difficult to make the opticaldensity high.

The recording paper to be applied in the ink jet recording system isgenerally made from bleached chemical pulp to which fillers, dyes and,if required, sizing agents and strength improvers are added.

There have heretofore been proposed several types of papers for ink jetrecording. For instance, Japanese Laid-open Patent Application No.52-74340 discloses an ink jet recording paper which is characterized inthat a ratio of an air resistance to basis weight (g/m²) (airresistance/basis weight) is below 0.3 and that when an aqueous ink forink jet recording is dropped in an amount of 0.004 ml, an absorptiontime of ink is in the range of from two seconds to 60 seconds. Further,Japanese Laid-open Patent Application No. 52-53012 teaches a method ofmaking recording papers which is characterized by applying a coating toa base paper which has been incorporated with a wet strength improverknown per se and which has a Stockigt sizing degree of below 1 secondwhereby the resulting surface coated paper has a Stockigt sizing degreeof below 3 seconds. In these laid-open patent applications, there aredescribed surface sizing agents including oxidized starch, PVA,galactomannon gum, polyacrylamide, sodium alginate, styrene-maleic acidcopolymer, CMC and other cellulose derivatives, casein, soy bean proteinand the like. In addition, there are mentioned, as sizing additives,hydrophobic materials or latices, rosin and its derivatives, petroleumresins, fumaric acid, maleic acid its derivatives, waxes, syntheticresins, fatty acids, alkylketene dimers and the like, and, as pigment orfiller, kaolin, calcium carbonate, aluminium hydroxide, satin white,titanium oxide, and urea-formalin organic fillers.

Moreover, there is proposed in Japanese Laid-open Patent Application No.55-5830 a sheet for ink jet recording which comprises a support and anink-receptive layer formed on the surface of the support, said sheethaving an opacity of 55.0 to 97.5%, an absorptivity of the ink-receptivelayer being in the range of 1.5 to 18.0 mm/min. Also, Japanese Laid-openPatent Application No. 55-11829 teaches a sheet for ink jet recordingwhich has (1) two or more layers, (2) an opacity of 55.0 to 97.5%, (3) atop layer with a thickness of 1.0 to 16.0 microns, and (4) anink-receptivity of the top layer of 1.5 to 5.5 mm/min and that of asecond layer of 5.5 to 60.0 mm/min.

The ink-receptive layer of these sheets is formed of white pigments suchas clay, talc, diatomaceous earth, calcium carbonate, calcium sulfate,barium sulfate, titanium oxide, zinc oxide, zinc sulfide, satin white,aluminium silicate, lithopone and the like. As binder resin, there arementioned oxidized starch, etherified starch, gelatin, casein,carboxymethyl cellulose, hydroethyethyl cellulose, polyvinyl alcohol andSBR latex.

We have made an extensive studies of ink jet recording papers whichsatisfy the afore-mentioned requirements (1) to (4) and found thatcoating layers made of combinations of sizing agents or binder resinsand pigments and fillers which have been known from the prior laid-openpatent applications do not show satisfactory characteristics whenapplied for such recording purpose. Especially, the resins serving asthe sizing agent or binder play an important role and it has been foundthat the known resins are unsatisfactory in ink receptivity and thusrecorded matter using such resins as a surface coating frequently showsinsufficient optical density.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to provide an jetrecording sheet which shows an improved optical density, when recorded,over prior art counterparts.

It is another object of the invention to provide an ink jet recordingsheet which shows an excellent ink receptivity and is able to suppressink dots from spreading.

It is a further object of the invention to provide an ink jet recordingsheet which ensures a certain extent of water proof and excellentfastness of light of recorded matter.

According to one aspect of the present invention, there is provided arecording sheet for ink jet recording comprising a paper support appliedwith a composition on at least one surface thereof, the compositioncomprising an aqueous dispersion of a binder resin selected from thegroup consisting of polyvinylpyrrolidone, vinyl pyrrolidone-vinylacetate copolymer and a mixture thereof which are soluble in water and awhite filler used in a weight ratio to the binder of 10:1 to 0.2:1, thecomposition being applied in an amount of 3 to 50 g/m² on a dry basis.

According to another aspect of the present invention, there is provideda recording sheet for ink jet recording which is made from a compositioncomprising a mixture of 100 parts by weight of a stock pulp, 10-60 partsby weight of a while filler, and 2-20 parts by weight of a binder resinselected from the group consisting of polyvinylpyrrolidone, vinyl andpyrrolidone-vinyl acetate copolymer and a mixture thereof.

The above and other objects, features and advantages of the presentinvention will become apparent from the following description and theappended claims.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION

As having described hereinabove, one of features of the presentinvention resides in use of polyvinyl-pyrrolidone (hereinafterabbreviated as PVP) and/or vinyl-pyrrolidone-vinyl acetate copolymer(hereinafter abbreviated as PVP/VAc). The PVP and PVP/VAc arewater-soluble polymers and have a film-forming property. They areindustrially applied as cosmetics, medical supplies, adhesives, cleaningagents and soaps, fiber-finishing agents, and inks, and also in thefield of lithographic printing and paper. PVP and PVP/VAc which areapplied in the field of the paper-making industry are used as adecoloring agent for rags for regeneration, an improver of cellulosepaper to improve its tensile strength, and a binder for the specifictype of paper made of inorganic flakes or fibers.

When applied to inks making use of dyes, PVP renders the dye morereadily soluble, serves to prevent gelation, and imparts deep color toneto even inks of low concentration of dye.

The PVP and PVP/VAc is soluble in water and have generally an averagemolecular weight of several thousands to several hundred thousands.These polymers may be ones which are prepared by any of know techniques.

The commercially available vinylpyrrolidone and vinyl acetate copolymerhas a ratio of PV/VAc generally in the range of 70/30 to 30/70.

The PVP and/or PVA/VAc is used in the practice of the invention togetherwith a white pigment or filler. Examples of the filler which ispreferably used in combination with the PVP resin or PVP/VAc copolymeras will become apparent from examples appearing hereinafter includeclay, talc, calcium carbonate, calcium sulfate, calcium silicatediatomaceous earth, magnesium silicate, terra abla, activated clay,magnesium oxide, magnesium carbonate and aluminium hydroxide. Aside fromthese, fillers which are ordinarily employed in the paper-makingindustry such as titanium oxide, silica, aluminium silicate, satinwhite, zinc oxide and the like may be usable though they are inferior inoptical density and the other characteristics to those mentioned above.

In one aspect of the invention, an aqueous dispersion of the PVP and/orPVP/VAc and the filler is applied onto at least one surface of papersupport. The dispersion can be readily prepared by adding a filler of apowder form to an aqueous solution of the PVP and/or PVP/VAc. In thiscase, a ratio of the filler to the resin is generally in the range of10:1 to 0.2:1, preferably 1:1 to 1:2. This will be particularlydescribed in examples appearing hereinafter. The aqueous dispersion isapplied to a paper support, which may be any of papers ordinarilyemployed for ink jet recording purpose, in an amount of 3 to 50 g/m² onthe dry basis. Preferably, the coating amount is in the range of about10 to 30 g/m² and most preferably about 20 g/m².

In order to improve water proof, the PVP and/or PVP/VAc resin may beadmixed with a sizing agent or binder which is ordinarily employed inthe paper-making industry, including, for example, oxidized starch, PVA,styrene-maleic acid copolymer, CMC, and hydroxyethylcellulose. When themixture is used, the PVP and/or PVP/VAc resin should be contained in anamount of not smaller than 33 wt% of the mixture when an added sizingagent shows little or no water absorptivity and in an amount of notsmaller than 20 wt% of the mixture when an added sizing agent showswater absorptivity such as PVA.

When it is desired to control a hardness of the PVP/VAc film, there maybe added to the aqueous dispersion or composition as usual plasticizerssuch as dimethyl phthalate, glycerine, diethylene glycol, sorbitolallysulfonamide-formaldehyde, cellulose butyrate, cellulosebutyrate-propionate and the like.

In another aspect of the present invention, the aqueous dispersion orcomposition is mixed with stock pulp and then an ink jet recording paperis made from the mixture by any of known paper-making techniques. Thepaper incorporating therein the PVP and/or PVP/VAc resin and fillercomposition has several advantages: The making process is simple; andThe PVP or PVP/VAc is readily soluble in water and is thus poor in waterproof, so that when a PVP or PVP/VAc-coated paper is dipped in water,the coating layer is readily dissolved out but the internallyincorporated paper has a certain degree of water proof though the fileris surely come off from the paper when dipped in water. This isexperimentally confirmed that when a surface coated recording paper isvertically dipped in water, a coating layer composed of PVP or PVP/VAcand white filler is come off from the paper support in 5 to 10 seconds.On the other hand, even when the internally incorporated recording paperis dipped in water for 10 seconds, only several percent of filler isfound to be come off from the paper. In addition, it takes over oneminute before the pulp stock of the paper itself is reduced into piecesand dispersed in water. As a matter of course, such a time variesdepending on the amount of PVP or PVP/VAc. A reason why the water proofis improved by internally applying the composition is believed due tothe fact that the resin or binder component is uniformly mixed with apulp component and thus the speed of infiltration of water becomes slowand no coating layer is come off as will be experienced in the case ofthe surface coating.

The internally applied recording paper can be made by one step withoutinvolving an additional coating process and is thus much simpler inmanufacturing step than the surface-coated recording paper.

However, the resin and filler are usually in the case in amounts greaterthan those required for the surface coating technique. That is, ashaving defined hereinbefore, the PVP and/or PVP/VAc is used in an amountof 2 to 20 parts by weight and a white filler is used in an amount of 10to 60 parts by weight both per 100 parts by weight of stock pulp. Theamount of the white filler, of course, varies more or less depending onthe type of the filler.

In order to further and much improve the water proof of either type ofthe recording papers, it is favorable to add to the PVP or PVP/VAc resinbinder an aqueous emulsion-type resin or a polymer soluble in alcoholwhich is capable of forming a water-proof film after drying.Water-soluble resin binders such as oxidized starch, PVA, CMC,hydroxyethyl cellulose and the like serve to improve the water proof ashaving described hereinbefore when used in combination with PVP ofPVP/VAc but are not potential for such purpose. For instance, thecoating layer obtained from the mixture of the water-soluble resinbinder and PVP or PVP/VAc is dissolved in water in about 10 to 15seconds and an increasing amount of the water-soluble resin binder givesan adverse influence of ink receptivity.

Examples of the aqueous emulsion useful in the practice of the inventionare those of polyvinyl acetate, ethylene-vinyl acetate copolymer (havingan ethylene content of below 30%), acrylic esters, water-soluble shellacand the like. Examples of polymers soluble in alcohol include polyvinylbutyral, polyacrylamide, polyamide-epichlorohydrin, shellac, polyvinylacetate and the like. These resins are capable of forming films ofrelatively good water proof after drying. The amount of these resinsvary depending on the type of resin and other factors including the typeand amount of filler and the thickness of coating layer, but isgenerally in the range of 1 to 50 wt%, preferably 2 to 20 wt%, of amixture of the resin and PVP or PVP/VAc.

In addition to these resins, various additives may be added to the PVPor PVP/VAc and filler. In particular, the resistance or the fastness tolight of recorded matter is one of important problems to solve.

Then, we have made an intensive study on the light fastness orresistance. The most general way of improving the fastness to light ofrecorded matter is to use dyes which are excellent in fastness to light.However, since inks to be employed in the ink jet recording system arerequired not to cause clogging of ink jet nozzles and to have a clearcolor tone, dyes with excellent light fastness cannot always beemployed. Basic dyes, acid dyes, or mordant dyes are clear in color toneand are now widely used for the ink jet recording purpose but these dyesare not necessarily excellent in light fastness.

The improvement of light fastness of recorded matter can be realized byadding to the aqueous dispersion or composition of PVP and/or PVP/VAcand filler (1) antioxidants, (2) UV absorber and (3) metal oxides, metalchlorides or tannic acid capable of reacting with dyes to convert thedyes into light-fast dyes.

During the course of our study, we have found that though the lightfastness more or less depend on the type of dye, the light fastness ofrecorded matter is poorer than that of dye in liquid state and thefading is mainly caused by photooxidation based on oxygen in air andlight. To prevent this, antioxidants have been found to be effective.Moreover, an investigation was conducted to know the mechanism of thefading in relation to wavelength. That is, glass filters were used toselect desired ranges of wavelength and a Xenone fade meter was used tomeasure the resistance to light of recorded matter. As a result, it wasfound (1) that little fading took place in the wavelength range ofinfrared rays, (2) that in the range of visible light, fading occurredin a wavelength corresponding to a main absorption peak of dye; (3) thatfading by the ultraviolet light was as great as in (2).

For instance, a magenta ink composed of 79% of water, 20% of ethyleneglycol and 11% of Basic Violet showed light resistance as follows.

    ______________________________________                                         ##STR1##                                                                     ______________________________________                                               250-320                                                                              2.32                                                                   320-380                                                                              1.25                                                                   440-520                                                                              0.97 -520-620 2.42 -Over 620 0.024                              ______________________________________                                    

From the results, it was considered that UV absorbers were effective toprevent fading of recorded matter, which was experimentally found ture.

These antioxidants, UV absorbers, and compounds capable of convertingdyes into light-resistant dyes or pigments are used in amounts of 0.1 to10 wt% of a mixture of the PVP or PVP/VAc and filler. These additivesare discussed in examples.

Then, the present invention is particularly described by way ofexamples, which should not be construed as limiting the presentinvention.

It will be noted here that four types of PVP were used having averagemolecular weights of 360,000 (hereinafter referred to as K-90), 160,000(hereinafter referred as K-60), 40,000 (hereinafter referred to as K-30)and 10,000 (hereinafter referred to as K-10) but little or nosubstantial difference in recording characteristics was observed amongthem and K-30 was used as the representative of PVP in examples. Inaddition, four types of PVP/VAc having VP/VAc ratios of 70/39, 60/40,50/50 and 30/70, respectively, were used to check recordingcharacteristics. As a result it was found that good results wereobtained in any cases without showing any significant differences amongthem. Accordingly, a PVP/VAc resin having a VP/VAc ratio of 50/50 wasused in examples as the representative for the PVP/VAc.

The ink jet recording was carried out using an On-demand-type head witha diameter of nozzle of 40 microns in which three ink jetting heads wereused to discharge therefrom different types of inks including cyan,yellow and magenta. By the combination of these inks, different colorsof red, green, blue and sepia were made. The discharge of ink waschanged in seven stages by controlling an application voltage and therecording of 6 lines/mm was conducted. In the case of monochrome,amounts of discharge per unit area in the respective stages are 2.6×10⁻⁴cc/cm² in first stage, 4.7×10⁻⁴ cc/cm² in second stage, 6.4×10⁻⁴ cc/cm²in third stage, 7.0×10⁻⁴ cc/cm² in fourth stage, 7.9×10⁻⁴ cc/cm² infifth stage, 8.7×10⁻⁴ cc/cm² in sixth stage, and 9.4×10⁻⁴ cc/cm² inseventh stage, respectively. In the case of blue in color, the amountsof discharge in the respective stages become double and in the case ofsepia color, they become three times. Accordingly, the severestrecording conditions are those for the sepia color in the seventh stage.Aside from these recordings, a recording of 2 lines/mm was alsoconducted for comparison.

Recorded matters were evaluated according to the following measurementsor observations: (1) Measurement of optical drensity of the respectivecolors in the seventh stage; (2) Judgement of a stage of sepia colorwhere inks start to run or spread so as to check a degree of the runningor spreading of the inks (which show a degree of ink receptivity ofpaper); (3) Measurement of a time before the sepia color of the seventhstage is apparently dried after application thereof; and (4) Measurementof a rate of area of recorded matter of the first stage in which twolines/mm were recorded (to know a degree of spreading of ink dots or adegree of so-called sharpness.

EXAMPLE 1

In this example, calcium carbonate was used as a white pigment anddifferent types of binder resins were used including PVP and PVP/VAc tobe used in the present invention.

To a 5% aqueous solution or dispersion of each binder resin was added 15wt% of calcium carbonate of a powder form having a size of 0.1 to 0.2microns, followed by fan agitating to give a slurry. This slurry wasapplied onto a commercially available groundwood paper by means of awire bar, followed by roll pressing to obtain a surface-coated paper.The coated layer had a thickness of 5 to 20 microns, i.e. 0.3-2.0 g ofthe coating was applied onto an A-4 size paper.

The respective recording papers thus made were subjected to therecording procedure and evaluated according to the measuring methodsdescribed hereinabove. The test results are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                           Stage                                                                         where                                                                         spreading Drying                                                     Optical  starts to time    Rate of                                  Binder resin                                                                            density  appear    (seconds)                                                                             area (%)                                 ______________________________________                                        PVP       1.03     >7        <10     14.4                                     PVP/VAc   0.99     >7        <10     14.8                                     Oxydized  1.14     4         180     11.2                                     starch                                                                        Polyacryl-                                                                              0.52     2         200     20.5                                     amide                                                                         PVA       0.96     6          60     15.0                                     Sodium    0.83     4         180     20.1                                     aluginate                                                                     Styrene-  0.78     4         250     22.2                                     maleic acid                                                                   copolymer                                                                     CMC       0.87     5         220     17.6                                     Casein    0.82     3         320     13.2                                     Soybean   0.72     3         300     14.6                                     protein                                                                       Gelatin   0.83     5         240     21.5                                     SBR latex 0.69     4         450     18.9                                     Hydroxyethyl                                                                            0.85     6          80     18.2                                     cellulose                                                                     Etherified                                                                              0.69     5         170     17.6                                     starch                                                                        ______________________________________                                    

In this table, the optical density was determined with respect to themagenta color of the seventh stage and other six colors showed a similartendency.

As will be clearly seen from the results of Table 1, the binder resingives a great influence on the characteristics of ink spreading, dryingtime and the like and the PVP/VAc resins involve no spreading or runningat the seventh stage and are thus much more excellent than the otherbinder resins. PVA and hydroxyethyl cellulose rank second to PVP andPVP/VAc with respect to optical density but these resins were inferiorin spreading characteristic, i.e. spreading occurred at the sixth stage,and required a drying time of as long as 60 to 80 seconds. As to theoptical density and rate of area, oxidized starch was excellent and PVPand PVP/VAc showed such characteristics next to oxidized starch.

EXAMPLE 2

In this example, PVP and PVP/VAc were used as a binder resin anddifferent types of white pigments were used in combination forcomparative purpose.

To a 10% aqueous solution of PVP or PVP/VAc was added each of whitepigments to be tested to give a slurry in the same manner as in Example1 and the slurry was applied in the same manner as in Example 1 toobtain a surface coated paper. The type and amount of white pigment andthe results of recorded matter are shown in Table 2 below with regard tothe PVP binder resin.

                  TABLE 2                                                         ______________________________________                                                        Stage                                                         White           where                                                         pigment         spreading                                                                              Drying Rate of                                                                             Whitely                                 (amount Optical starts to                                                                              time   area  fading                                  by wt.) density appear   (seconds)                                                                            (%)   phenomenon                              ______________________________________                                        clay    1.11    6        15     13.7  no                                      (20%)                                                                         talc    1.00    >7       <10    11.5  no                                      (20%)                                                                         calcium 1.11    >7       <10    14.9  no                                      carbonate                                                                     (20%)                                                                         calcium 0.97    >7       <10    12.0  no                                      sulfate                                                                       (20%)                                                                         calcium 0.97    >7       <10    10.4  no                                      silicate                                                                      (10%)                                                                         diato-  0.98    7        <10    16.5  no                                      maceous                                                                       earth                                                                         (15%)                                                                         aluminium                                                                             0.92    7        14     13.9  no                                      hydroxide                                                                     (20%)                                                                         titanium                                                                              0.85    6        15     14.8  yes                                     oxide                                                                         (20%)                                                                         silica  0.82    7        20     14.5  yes                                     (20%)                                                                         aluminium                                                                             0.87    7        20     10.9  yes                                     silicate                                                                      (20%)                                                                         satin   0.80    7        15     11.7  yes                                     white                                                                         (20%)                                                                         zinc    0.87    7        15     13.9  yes                                     oxide                                                                         (20%)                                                                         ______________________________________                                    

As will be appreciated from the results of Table 2, with titanium oxide,silica, aluminium silicate, satin white and zinc oxide, there appears awhitely fading phenomenon where an entirety of image is observed aswhite and the optical density does not become higher than 0.9. This isbecause an ink does not remain on the surface of the coated paper andthe white pigment deposits out on the paper surface. In contrastthereto, clay, talc, calcium carbonate, calcium sulfate, calciumsilicate, diatomaceous earth and aluminium hydroxide show no fadingphenomenon and optical densities of above 0.9. The white pigmentscausing the fading phenomenon cannot be used in large amounts and do notshow an effect of increasing the whiteness of paper though usable in thepractice of the invention. In this sense, the white pigments showing nofading phenomenon are conveniently and preferably used. Preferablepigments further include magnesium silicate, terra abla, activated clay,magnesium oxide and magnesium carbonate. As regards the spreadingcharacteristic and drying time, there is not a significant differencedepending on the type of pigment, revealing that such characteristicsare mainly dependent of the type of binder.

In Table 2, the binder used was PVP and similar results were obtainedwhen PVP/VAc was used except that the optical density was reduced byabout 0.5 in all the cases.

EXAMPLE 3

In this example, PVP was used as binder resin and calcium carbonate,calcium silicate and talc were used as pigment to determine an effect ofa ratio by weight of the binder and the white pigment on the recordingcharacteristics. The coated paper was made in the same manner as inExample 1. In Table 3, there are shown results of a test using calciumcarbonate.

                  TABLE 3                                                         ______________________________________                                                               Stage                                                                         where         Rate Whitely                                                    spreading                                                                            Drying of   fading                              PVP  Calcium   Optical starts to                                                                            time   area pheno-                              (%)  carbonate density appear (seconds)                                                                            (%)  menon                               ______________________________________                                         2   20        0.85     7      15    14.8 yes                                  5   20        0.98    >7     <10    16.3 no                                  10   20        1.11    >7     <10    13.0 no                                  15   20        1.19    >7     <10    12.2 no                                  20   20        1.24    >7     <10     6.5 no                                  20   15        1.12    >7     <10     9.7 no                                  20   10        0.97    >7     <10    11.6 no                                  20    5        0.84    >7     <10    14.8 no                                  20    2        0.75    >7     <10    20.0 no                                  20    1        0.58    >7     <10    32.0 no                                  ______________________________________                                    

As will be clear from the results of Table 3, high optical densitycannot be obtained when amounts of PVP and calcium carbonate are toogreat or too small. That is, in order to obtain good recordingcharacteristics, a PVP/calcium carbonate (with an average size of 0.1 to0.2 microns) ratio by weight is preferably in the range of 10:1 to0.25:1. When a similar test was conducted using a calcium silicatepowder having an average particle size of 0.1 micron and a talc powderhaving an average size of 0.2 to 0.3 microns, it was found that apreferable weight ratio was in the range of 10:1 to 0.5:1 for calciumsilicate and 5:1 to 0.2:1 for talc. The weight ratio is, of course,dependent on the size of white pigment and the weight ratio of PVP orPVP/VAc and a white pigment is conveniently in the range of 10:1 to0.2:1.

Furthermore, when the composition comprising calcium carbonate and PVPwas applied in different thicknesses ranging from 4 microns to 28microns, no significant difference in recording characteristics wasfound in this range of thicknesses.

In addition, four types of paper support showing different waterabsorptivities were used to check their influence on the recordingcharacteristics. As a result, it was found that when the coated layerhad a thickness of above 8 microns, inclusive, good results wereobtained in any cases.

From the above, the coated layer should preferably have a thickness of 8microns or more, and the coating composition of the invention can bewidely applied to a wide variety of paper supports.

EXAMPLE 4

In this example, PVP and other binder resins were used in combination.As a white pigment, talc (Chinese talc) were used. Amounts of the binderresin and talc were, respectively, 20%. Coated papers were madesubstantially in the same manner as in Example 1, with the resultssummarized in Table 4 below.

                  TABLE 4                                                         ______________________________________                                                                  Stage                                                                         where                                                                         spreading                                                                             Drying Rate of                                        Weight  Optical starts  time   area                                 Binder resin                                                                            ratio   density appear  (seconds)                                                                            (%)                                  ______________________________________                                        PVP/PVA   1/1     0.94    >7      <10    12.9                                 PVP/PVA   1/2     0.94    >7      13     12.5                                 PVP/PVA   1/5     0.92    7       40     12.7                                 PVP/oxidized                                                                            1/1     1.10    >7      24     10.4                                 starch                                                                        PVP/oxidized                                                                            1/2     1.06    7       53     11.8                                 starch                                                                        PVP/oxidized                                                                            1/5     0.92    6       190    13.0                                 starch                                                                        PVP/styrene-                                                                            1/1     0.86    7       50     15.5                                 maleic                                                                        copolymer                                                                     PVP/styrene-                                                                            1/2     0.86    7       62     16.9                                 copolymer                                                                     PVP/styrene-                                                                            1/5     0.89    5       280    22.0                                 copolymer                                                                     PVP/-     1/1     0.93    >7      18     13.7                                 hydroxyethyl                                                                  cellulose                                                                     ______________________________________                                    

As will be appreciated from the above results, binder resins such asPVA, oxidized starch and the like show more excellent ink receptivitywheh applied in combination with PVP.

A greater amount of PVP is desirable in view of the ink receptivity.Though the content of PVP depends on the type of the second binder, itis in the range of over 20 wt% when the binder resin used in combinationwith PVP shows water absorptivity such as PVA and in the range of 33 wt%when the second binder resin shows no water absorptivity.

EXAMPLE 5

In this example, characteristics of ink jet recording papers made by asize press technique are described.

Different types of binder and calcium carbonate were mixed in a ratio of1:1 in an aqueous medium to obtain 10% slurries. Each slurry was coatedon a commercially available groundwood paper by a size press system toobtain a surface coated paper with a coating spread of 4.0 g/m². Theresults are shown in Table 5 below.

                  TABLE 5                                                         ______________________________________                                                                  Stage                                                                         where                                                                         spreading                                                                             Drying Rate of                                        Weight  Optical starts  time   area                                 Binder resin                                                                            ratio   density appear  (seconds)                                                                            (%)                                  ______________________________________                                        PVP               1.18    >7      <10    11.0                                 PVP/VAc           0.98    >7      <10    13.0                                 PVP/PVA   1/1     0.96    >7      18     14.7                                 PVP/-     1/1     1.14     7      20     12.5                                 oxidized                                                                      starch                                                                        ______________________________________                                    

From the above results, it will be seen that the characteristics of therecording papers made by the size press technique are substantially thesame as those of the recording papers obtained by the wire bar. Forinstance, the recording paper of the coated type using PVP/VAc as binderhad an optical density of 0.99, a spreading stage of >7, a drying timeof 21 10, and a rate of area of <10 as shown in Table 1, which arealmost the same as those of Table 5. In the PVP/PVA and PVP/oxidizedstarch systems, the recording characteristics are almost the same asthose of Table 4. Accordingly, the size press technique can be usedsimilarly with the surface coating method.

EXAMPLE 6

In this example, binder resins and calcium carbonate used as whitepigment were applied internally or mixed with pulp.

LBKP and NBKP were mixed in a ratio of 1:2 and beaten in a refiner.Then, light calcium carbonate was added to the pulp in an amount of 30parts by weight per 100 parts by weight of the pulp and PVP or PVP/VAcwas added in an amount of ranging from 0.5 to 30 wt% based on the pulp.The pulp composition was subjected to a paper-making process using aFourdriner test machine to make a paper with a basis weight of 70 g/m².The thus made papers were each subjected to the calender rolls to giverecording papers.

The recording papers were applied with inks and evaluated in the samemanner as described hereinbefore, with the result shown in Table 6below.

                  TABLE 6                                                         ______________________________________                                                                   Stage                                                                         where                                                                         spreading                                                                            Drying Rate of                                        Amount   Optical starts to                                                                            time   area                                 Binder resin                                                                            (%)      density appear (seconds)                                                                            (%)                                  ______________________________________                                        PVP       0.5      0.80     6      15    19.3                                 PVP        1       0.85     7      10    17.5                                 PVP        2       0.96    >7     <10    15.6                                 PVP        5       0.98    >7     <10    15.4                                 PVP       10       1.00    >7     <10    15.0                                 PVP       20       1.00    >7     <10    15.1                                 PVP       30       1.01    >7     <10    15.3                                 PVP/VAc   0.5      0.72     5      20    20.1                                 PVP/VAc    1       0.82     6      15    17.9                                 PVP/VAc    2       0.92     7      10    16.1                                 PVP/VAc    5       0.95    >7      10    16.0                                 PVP/VAc   10       0.98    >7     <10    15.9                                 PVP/VAc   20       0.98    >7     <10    15.9                                 PVP/VAc   30       0.98    >7     <10    15.5                                 ______________________________________                                    

In the table, the optical density is obtained from the magenta color ofthe seventh stage and as regards the other six colors, a similartendency is observed.

As will be appreciated from the above results, where the binder contentis 0.5% or 1%, the optical density, stage where spreading appeared,drying time and rate of area are not satisfactory. Accordingly, thebinder resin should be contained in an amount of at least 2% of thepulp. This is much larger as compared with an amount of an strengthimprover ordinarily employed in the paper-making industry (generally inthe range of 0.2 to 1 wt%). On the other hand, the recording papers inwhich 30% of PVP or PVP/VAc based on the pulp is contained showexcellent recording characteristics but become sticky to the touch. Inaddition, such papers show a blocking tendency.

Gathering the above, the content of PVP or PVP/VAc is in the range of 2wt% to 20 wt% of the pulp.

EXAMPLE 7

In this example, an amount of PVP was set at 10% by weight of pulp butan amount of calcium was changed. Recording papers were each made andevaluated in the same manner as in Example 6. The test results are shownin Table 7 below.

                  TABLE 7                                                         ______________________________________                                                                  Stage                                                                         where                                                                         spreading                                                                             Drying Rate of                                       Amount   Optical starts to                                                                             time   area                                 White filler                                                                           (%)      density appear  (seconds)                                                                            (%)                                  ______________________________________                                        calcium   3       0.83     7       20    21.0                                 carbonate                                                                     calcium   5       0.91     7       15    16.5                                 carbonate                                                                     calcium  10       0.96    >7      <10    15.2                                 carbonate                                                                     calcium  20       1.01    >7      <10    14.9                                 carbonate                                                                     calcium  40       1.00    >7      <10    15.0                                 carbonate                                                                     calcium  50       0.97    >7      <10    14.1                                 carbonate                                                                     calcium  60       0.83    >7      <10    12.4                                 carbonate                                                                     calcium  70       0.45    >7      <10    10.3                                 carbonate                                                                     ______________________________________                                    

As will be apparent from the above results, good recordingcharacteristics are obtained when the content of the white filler is inthe range of 10 to 60 wt% of the pulp. Less contents are disadvantageousin that the optical density is poor while larger contents lead to thewhitely fading phenomenon. Accordingly, an effective amount of calciumcarbonate is in the range of 10 to 60 wt% of the pulp. In thisconnection, the content of calcium carbonate more or less depends on thecontent of PVP, e.g. when the content of PVP is 2%, the upper limit incontent of calcium carbonate was found to be 40%. Similar results wereobtained when PVP/VAc was used instead of PVP.

The above procedure was repeated using other several white pigments indifferent amounts. As a result, it was found that a suitable content ofclay was in the range of 10 to 60 wt% of the pulp, that of talc rangedfrom 10 to 60 wt%, that of calcium sulfate ranged from 5 to 40 wt%, thatof calcium silicate ranged from 10 to 40 wt%, that of diatomaceous earthranged from 10 to 60 wt%, that of satin white ranged from 5 to 50 wt%,and that of zinc oxide ranged from 15 to 40 wt%. Generally speaking,white pigments are effectively usable in tha range of 10 to 60 wt% ofpulp. Other usable white pigments in this internal application techniqueare aluminium hydroxide, silica, aluminium silicate, magnesium silicate,terra abla, activated clay, magnesium oxide, magnesium carbonate,aluminium oxide and the like. Among the white pigments, preferable onesare those mentioned with respect to the surface coating method.

The following three examples illustrate water-proof, film-forming resinsadded to the basic composition used in the present invention.

EXAMPLE 8

In this example, binder resin made of 90 parts by weight of PVP and 10parts by weight of different types of film-forming polymers were used.

To 10% aqueous or alcoholic solutions of various binder resin mixtureswas added calcium carbonate powder with a size of 0.1 to 0.2 microns inan amount of as great as three times the binder resin mixture, followedby agitating with a fan to give slurries. Each slurry was applied onto acommercially available groundwood paper by a wire bar and the thusapplied paper was roll pressed to obtain surface coated papers. Thethickness of the coated layer was in the range of 5 to 20 microns. Thethus obtained papers were recorded and evaluated in the same manner asin Example 1 except for water proof. That is, the water proof wasevaluated as follows: a time before the coated layer was completelyseparated from a coated paper specimen with a size of 1 cm×2 cm afterhaving immersed the coated paper vertically in water was measured. Thetest results are shown in Table 8 below.

                  TABLE 8                                                         ______________________________________                                                          Stage                                                                         where ink                                                                     spreading Drying Rate of                                    Binder resin                                                                            Optical starts to time   area  Water                                mixture   density appear    (seconds)                                                                            (%)   proof                                ______________________________________                                        PVP       1.03    >7        <10    14.4   5                                   PVP/VAc   0.99    >7        <10    14.8   5                                   PVP + oxidiz-                                                                           1.11    >7        14     10.0   7                                   ed starch                                                                     PVP + PVA 1.00    >7        10     12.2   5                                   PVP + hydro-                                                                            0.98    >7        12     13.1   5                                   xyethyl                                                                       cellulose                                                                     PVP + poly-                                                                             0.95    7         15     14.5  25                                   vinyl                                                                         acetate                                                                       PVP + ethyl-                                                                            0.94    7         19     13.9  30                                   ene/vinyl-                                                                    acetate                                                                       copolymer                                                                     PVP + acrylic                                                                           0.97    7         17     13.9  25                                   ester resin                                                                   PVP + water-                                                                            1.01    7         13     12.8  40                                   soluble shellac                                                               PVP + poly-                                                                             0.98    7         15     14.5  35                                   vinyl                                                                         butyral*                                                                      PVP + poly-                                                                             0.95    7         14     14.3  20                                   acryl-                                                                        amide*                                                                        PVP + poly-                                                                             0.93    7         14     13.9  25                                   amide · epi-                                                         chloro-                                                                       hydrin*                                                                       PVP +     1.00    7         13     14.5  60                                   shellac*                                                                      ______________________________________                                         *Note:                                                                        These resins were dissolved in methanol.                                 

From the above results, it will be appreciated that when PVP or PVP/VAcis used singly, the water proof is 5 seconds or less. In addition,systems of PVP or PVP/VAc to which other water-soluble polymers such asoxidized starch, PVA and hydroxyethyl cellulose have been added show aslight improvement in water proof. On the other hand, binder resinmixtures in which 10 wt% of aqueous emulsion-type polymers such aspolyvinyl acetate, ethylene-vinyl acetate copolymer, acrylic ester resinand water-soluble shellac show a water proof of over 25 seconds, thusimproving the water proof remarkably. These binder resin mixtures areslightly inferior in recording characteristics, i.e. the spreading stageof seven and a drying time of 13-19, to the PVP or PVP/VAc resin alone.However, these slight degrees of deterioration of the characteristicsare almost negligible and the improvement in water proof is much moreeffective. Similar results are obtained when polyvinyl butyral,polyacrylamide, polyamide.epichlorohydrin, shellac and the like are usedas dissolved in methanol solvent.

Aside from the resins mentioned above, other resins are also usable incombination with PVP and/or PVP/VAc including vinylacetate-acrylonitrile complymer, styrene resin, styrene-acrylonitrilecopolymer, methacrylic ester resin, polyamide resin, malamine resin,melamine-urea resin and the like.

EXAMPLE 9

In this example, an influence of polyvinyl acetate in a binder resincomposed of PVP and polyvinyl acetate was checked. To an aqueous 10%solution of the binder resin was added talc (Chinese talc) in an amountof two times the binder resin to give a slurry. Then, Example 8 wasrepeated with the results shown in Table 9.

                  TABLE 9                                                         ______________________________________                                                                Stage                                                                         where ink     Rate                                                            spreading                                                                             Drying                                                                              of                                      Binder  Weight  Optical starts to                                                                             time  area Water                              resin   ratio   density appear  (sec) (%)  proof                              ______________________________________                                        PVP/poly-                                                                             98/2    1.04    7       10    14.7  5                                 vinyl                                                                         acetate                                                                       PVP/poly-                                                                             95/5    1.02    7       12    14.3 18                                 vinyl                                                                         acetate                                                                       PVP/poly-                                                                             90/10   0.97    7       15    14.8 25                                 vinyl                                                                         acetate                                                                       PVP/poly-                                                                             80/20   0.98    7       19    14.2 33                                 vinyl                                                                         acetate                                                                       PVP/poly-                                                                             60/40   0.95    7       20    14.2 45                                 vinyl                                                                         acetate                                                                       PVP/poly-                                                                             50/50   0.95    6       23    14.7 60                                 vinyl                                                                         acetate                                                                       PVP/poly-                                                                             40/60   0.93    5       49    15.2 100                                vinyl                                                                         acetate                                                                       PVP/poly-                                                                             20/80   0.93    5       125   16.6 120                                vinyl                                                                         acetate                                                                       ______________________________________                                    

As will clear from the above results, the proof to water is moreimproved as the amount of polyvinyl acetate is increased. However, theoptical density, spreading characteristic and drying time become moredeteriorated with an increasing amount of polyvinyl acetate. Forinstance, the drying time is 49 seconds for the binder system ofPVP/polyvinyl acetate=40/60. This time is longer than a time of fromcompletion of image formation till withdrawal of the recorded matterfrom a machine and is not thus practical. Taking the above intoconsideration, a maximum amount of polyvinyl acetate should be 50%, i.e.it is necessary that polyvinyl acetate does not exceed that of PVP. Onthe other hand, the binder system containing 2% of polyvinyl acetatedoes show little effects and thus polyvinyl acetate should be over 2%.

The above procedure was repeated using different types of film-formingand water-proof polymers to determine the range of addition of eachpolymer which may more or less depend on the type and amount of whitepigment, and thickness of the coated layer. The results are shown inTable 10.

                  TABLE 10                                                        ______________________________________                                                               Possible range of                                      Binder resin           addition                                               ______________________________________                                        PVP/ethylene-vinyl acetate copolymer                                                                 98/2-60/40                                                                    on a weight basis                                      PVP/acrylic ester resin                                                                              98/2-60/40                                             PVP/water shellac      99/1-70/30                                             PVP/polyvinyl butyral  99/1-70/30                                             PVP/polyacrylamide     99/1-70/30                                             PVP/polyamide.epichlorohydrin                                                                        99/1-60/40                                             PVP/shellac            99/1-70/30                                             PVP.VAc/polyvinyl acetate                                                                            98/2-50/50                                             PVP.VAc/ethylene-vinyl acetate                                                                       98/2-60/40                                             copolymer                                                                     PVP.VAc/acrylic ester resin                                                                          98/2-60/40                                             PVP.VAc/water shellac  99/1-70/30                                             PVP.VAc/polyvinyl butyral                                                                            99/1-70/30                                             PVP.VAc/polyacrylamide 99/1-70/30                                             PVP.VAc/polyamide.epichlorohydrin                                                                    99/1-60/40                                             PVP/shellac            99/1-70/30                                             ______________________________________                                    

From the above results, it is generally possible to use these waterproof-imparting resins in the range of 1 to 50 wt% of the mixture withPVP or PVP/VAc provided that the type and amount of white pigment andthe thickness of the coated layer are properly controlled.

EXAMPLE 10

In this example, characteristics of ink jet recording papers made by thesize press technique are shown.

Various binders (PVP:additive polymer=90:10) and calcium carbonate weremixed in a weight ratio of 1:2 to give 10% slurries. Each slurry wasapplied onto a commercially vailable groundwood paper by the size pressmethod in an amount of 4.0 g/m² on a dry basis to give a surface coatedpaper. The thus obtained coated papers had recording characteristicsshown in Table 11.

                  TABLE 11                                                        ______________________________________                                                         Stage                                                                         where ink                                                                     spreading Drying Rate of                                                                             Water                                          Optical starts to time   area  proof                                 Binder resin                                                                           density appear    (seconds)                                                                            (%)   (seconds)                             ______________________________________                                        PVP      1.04    7         10     14.2   5                                    PVP/VAc  1.00    7         10     14.6   5                                    PVP/poly-                                                                              0.95    7         14     14.3  31                                    vinyl                                                                         acetate                                                                       PVP/-    0.98    7         20     14.0  23                                    acrylic                                                                       ester resin                                                                   PVP/poly-                                                                              0.97    7         15     14.3  40                                    vinyl                                                                         butyral                                                                       PVP/water                                                                              1.01    7         15     13.0  45                                    shellac                                                                       PVP/ethyl-                                                                             0.94    7         18     14.5  35                                    ene-vinyl                                                                     acetate                                                                       copolymer                                                                     PVP VAc/-                                                                              0.93    7         17     14.8  40                                    polyvinyl                                                                     acetate                                                                       ______________________________________                                    

As will be clearly seen from the above results, the characteristics ofthe recording papers made by the size press method are excellentsimilarly to those of the recording papers made by the wire bar coatingmethod. As for the water proof, the recording papers made by the sizepress method are slightly superior to those obtained by the wire barcoating method. Thus, the size press technique can be used similarlywith the surface coating method.

The following examples deal with the manner of imparting lightresistance to recorded matter in which antioxidants, Ultravioletabsorbers and compounds capable of reacting with dyes for convertioninto light-resistant dyes.

The measurement of light resistance was conducted according to a methodas prescribed in JIS L0843-71 using a 2.5 KW xenon fade meter of anair-cooling type (made by Suga Tester K.K.). The irradiation energy was464 J/cm².Hr, which is 9.6 times that of an average sunlight and 380times that of a fluorescent lamp.

The ink jet recording was carried out using an On-demand-type headhaving a nozzle diameter of 40 microns and a voltage of 200 V wasapplied to the recording system. When a recording of 6 lines/mm² waseffected, a discharge per unit area was 7.9×10⁻⁴ cc/cm².

Recording papers used were made by applying onto a commerciallyavailable high quality paper three types of coating compositioncomprising three types of binders of polyvinyl alcohol, oxidizedstarch/polyvinyl alconol (30/70) and polyvinylalcohol/polyvinylpyrrolidone (40/60) and calcium carbonate as whitefiller in a binder-to-filler ratio of 1:1, respectively. The coatingamount was 40 g/m². The three types of recording papers were designatedas recording papers A, B and C respectively. Antioxidants, UV absorbersand the specific type of compounds capable of reacting with dyes weredissolved in binder to make recording papers. It will be noted thatthese additives are effective for any recording papers which are to beapplied with dyes for recording purpose and application of theseadditives to recording papers outside the scope of the invention is alsodescribed in the following examples to evidence the excellency of theseadditives.

EXAMPLE 11

Various metal oxides and organic acids were added to the binders in suchan amount that they were contained in the surface coating in an amountof 0.5 g/m². Then, recording papers were made substantially in the samemanner as in the foregoing examples.

Then, a magenta ink made of 79% by weight of water, 20% by weight ofethylene glycol and 1% by weight of C.I. Basic Violet 10 was preparedand used for recording on the respective recording papers. The recordedpapers were irradiated for 12 hours in the xenone fade meter and theiroptical density was measured. The test results are shown in Table 12below.

                  TABLE 12                                                        ______________________________________                                                   Optical Density (O.D.)                                                              Irra-                                                        Rec-             diation  Irradiation                                         ording           time     time    O.D. (12 hours)/                            paper Additive   (0 hour) (12 hours)                                                                            O.D. (0 hours)                              ______________________________________                                        A     nil        0.93     0.41    0.44                                        A     pnosphorus 0.84     0.68    0.81                                              tungstic acid                                                           A     phosphorus 0.89     0.82    0.92                                              molybdic acid                                                           A     phosphorus 0.91     0.88    0.97                                              tungsten                                                                      molybdic acid                                                           A     chromic    0.88     0.83    0.94                                              chloride                                                                A     tannic     0.99     0.99    1.00                                              acid                                                                    B     nil        0.97     0.42    0.43                                        B     phosphorus 0.91     0.78    0.92                                              tungstic acid                                                           B     phosphorus 0.93     0.86    0.92                                              molybdic acid                                                           B     phosphorus 0.96     0.90    0.94                                              tungsten                                                                      molybdic acid                                                           B     chromic    0.89     0.84    0.94                                              chloride                                                                B     tannic     0.99     0.98    0.99                                              acid                                                                    C     nil        0.88     0.35    0.40                                        C     phosphorus 0.85     0.62    0.73                                              tungstic acid                                                           C     phosphorus 0.88     0.81    0.92                                              molybdic acid                                                           C     phosphorus 0.87     0.82    0.94                                              tungsten                                                                      molibdic acid                                                           C     chromic    0.81     0.76    0.94                                              chloride                                                                C     tannic     0.92     0.82    0.89                                              acid                                                                    ______________________________________                                    

As will be seen from the above results, the additives are found toremarkably improve the light resistance of recorded matter. In practice,the phosphorus-containing acids are preferably used because of theirexcellency in color retentivity.

EXAMPLE 12

Various inks composed of 76 to 79% by weight of water 20% by weight ofethylene glycol and 1 to 4% by weight of different types of dyes weremade and applied on a recording paper D which was made by applying 0.5g/m² of phosphorus molybdic acid to the recording paper A and arecording paper E applied with 0.5 g/m² of tannic acid similarly to thecase of the recording paper D.

The light resistance was measured in the same manner as in Example 11with the results shown in Table 13 below.

                  TABLE 13                                                        ______________________________________                                                   Optical Density (O.D.)                                                              Irra-                                                        Rec-             diation  Irradiation                                         ording           time     time    O.D. (12 hours)/                            paper Dye        (0 hour) (12 hours)                                                                            O.D. (0 hour)                               ______________________________________                                        A     C.I. Basic 0.57     0.39    0.69                                              Yellow 11                                                               D     C.I. Basic 0.59     0.49    0.83                                              Yellow 11                                                               E     C.I. Basic 0.61     0.52    0.85                                              Yellow 11                                                               A     C.I. Basic 0.79     0.35    0.44                                              Red 1                                                                   D     C.I. Basic 0.77     0.53    0.69                                              Red 1                                                                   E     C.I. Basic 0.71     0.51    0.72                                              Red 1                                                                   A     C.I. Basic 0.78     0.56    0.72                                              Red 3                                                                   D     C.I. Basic 0.75     0.54    0.85                                              Red 3                                                                   E     C.I. Basic 0.74     0.62    0.84                                              Red 3                                                                   A     C.I. Basic 0.97     0.37    0.38                                              Violet 14                                                               D     C.I. Basic 0.91     0.63    0.69                                              Violet 14                                                               E     C.I. Basic 0.93     0.69    0.75                                              Violet 14                                                               A     C.I. Basic 0.79     0.46    0.58                                              Blue 3                                                                  D     C.I. Basic 0.77     0.57    0.74                                              Blue 3                                                                  E     C.I. Basic 0.73     0.55    0.77                                              Blue 3                                                                  A     C.I. Mordant                                                                             0.41     0.30    0.73                                              Orange 4                                                                D     C.I. Mordant                                                                             0.39     0.30    0.77                                              Orange 4                                                                E     C.I. Mordant                                                                             0.42     0.32    0.77                                              Orange 4                                                                A     C.I. Mordant                                                                             0.77     0.59    0.77                                              Red 15                                                                  D     C.I. Mordant                                                                             0.72     0.61    0.85                                              Red 15                                                                  E     C.I. Mordant                                                                             0.75     0.67    0.89                                              Red 15                                                                  A     C.I. Mordant                                                                             0.71     0.62    0.87                                              Violet 5                                                                D     C.I. Mordant                                                                             0.73     0.67    0.92                                              Violet 5                                                                E     C.I. Mordant                                                                             0.68     0.62    0.91                                              Violet 5                                                                A     C.I. Mordant                                                                             0.82     0.75    0.91                                              Black 7                                                                 D     C.I. Mordant                                                                             0.79     0.75    0.95                                              Black 7                                                                 E     C.I. Mordant                                                                             0.83     0.78    0.94                                              Black 7                                                                 A     C.I. Acid  0.51     0.21    0.41                                              Yellow 17                                                               D     C.I. Acid  0.53     0.44    0.83                                              Yellow 17                                                               E     C.I. Acid  0.52     0.47    0.90                                              Yellow 17                                                               A     C.I. Acid  0.63     0.42    0.69                                              Orange 7                                                                D     C.I. Acid  0.63     0.49    0.78                                              Orange 7                                                                E     C.I. Acid  0.63     0.58    0.92                                              Orange 7                                                                A     C.I. Acid  0.80     0.38    0.47                                              Red 88                                                                  D     C.I. Acid  0.82     0.63    0.77                                              Red 88                                                                  E     C.I. Acid  0.78     0.70    0.89                                              Red 88                                                                  A     C.I. Acid  0.92     0.32    0.35                                              Violet 49                                                               D     C.I. Acid  0.95     0.71    0.75                                              Violet 49                                                               E     C.I. Acid  0.90     0.75    0.83                                              Violet 49                                                               A     C.I. Acid  0.81     0.72                                                .88                                                                                 Blue 7                                                                  D     C.I. Acid  0.80     0.77    0.96                                              Blue 7                                                                  E     C.I. Acid  0.83     0.81    0.98                                              Blue 7                                                                  A     C.I. Acid  1.00     0.83    0.83                                              Black 2                                                                 D     C.I. Acid  1.03     0.98    0.95                                              Black 2                                                                 E     C.I. Acid  1.03     1.02    0.99                                              Black 2                                                                 A     C.I. Acid  0.94     0.86    0.91                                              Black 31                                                                D     C.I. Acid  0.93     0.91    0.98                                              Black 31                                                                E     C.I. Acid  0.95     0.94    0.99                                              Black 31                                                                ______________________________________                                    

From the above results, it will be seen that the phosphorus molybdicacid and tannic acid showed a very remarkable effect of light resistanceon the basic dyes and acid dyes and a fair effect on the mordant dyes.However, little effects on the direct dyes and disperse dyes wererecognized.

In these examples 11 and 12, five compounds are illustrated and othereffective additives includes halides and oxides of at least one metalsuch as of barium, manganese, iron, copper, calcium, magnesium, cobaltand nickel.

The amount of these additives varies depending on the type thereof butis generally in the range of 0.1 to 10% by weight of the coatingcomposition in case of the surface-coated recording paper. Largeramounts give an adverse effect on the recording characteristics.

As will be appreciated from the results of Example 11, the additivesshow their light-resistant effect independently of the type of coating.Further, their effect is also developed when the additives areincorporated in paper or applied by dipping paper in solutions of theadditives. This is particularly described in Example 13 and 14.

EXAMPLE 1

A commercially available high quality paper showing a relatively highdegree of water absorptivity was used on which recording was conductedby an ink jet recording technique using an ink as used in Example 11.After completion of the recording, the recorded matter was dipped inacetone or methanol solutions of 2 wt% of phosphorus tungstic acid,phosphorus molybdic acid, phosphorus tungsten molybdic acid, chromicchloride and tannic acid, then dried, and subjected to the measurementof light resistance. The results are shown in Table 14.

                  TABLE 14                                                        ______________________________________                                                Optical Density (O.D.)                                                          Irradiation                                                                             Irradiation                                                         time      time       D.C. (12 hours)/                               Additive  (0 hour)  (12 hours) D.C. (0 hours)                                 ______________________________________                                        nil       0.88      0.40       0.45                                           phosphorus                                                                              0.91      0.66       0.73                                           tungstic acid                                                                 phosphorus                                                                              0.83      0.76       0.92                                           molybdic acid                                                                 phosphorus                                                                              0.88      0.85       0.97                                           tungsten                                                                      molybdic acid                                                                 chromic   0.83      0.79       0.97                                           chloride                                                                      tannic    0.95      0.93       0.98                                           acid                                                                          ______________________________________                                    

These additives can improve the light resistance of recorded matter whenapplied by the dipping method as will be seen from the above results.

EXAMPLE 14

LBKP having a freeness (C.S.F.) of 400 ml was used as stock pulp towhich were added 10 wt% of talc, 0.2 wt% of a wet strength improver and0.5 wt% of additives each based on the solid component of pulp. The thusadded pulps were each used to make papers with a basis weight of 50 g/m²in a usual manner.

Then, an ink with the same composition as used in Example 13 was used torecord on the thus made papers and the recorded matters were subjectedto the measurement of light resistance. The results are shown in Table15 below.

                  TABLE 15                                                        ______________________________________                                                Optical Density (O.D.)                                                          Irradiation                                                                              Irradiation                                                        time       time      D.C. (12 hours)/                               Additive  (0 hour)   (12 hours)                                                                              D.C. (0 hours)                                 ______________________________________                                        nil       0.82       0.40      0.49                                           phosphorus                                                                              0.86       0.68      0.79                                           tungstic acid                                                                 phosphorus                                                                              0.79       0.77      0.97                                           molybdic acid                                                                 phosphorus                                                                              0.84       0.80      0.95                                           tungsten                                                                      molybdic acid                                                                 chromic   0.79       0.71      0.90                                           chloride                                                                      tannic    0.91       0.89      0.98                                           acid                                                                          ______________________________________                                    

The additive-incorporated papers show improved light resistance over theadditive-free paper.

EXAMPLE 15

Example 11 were repeated using various antioxidants, with the resultsshown in Table 16 below, in which the three recording papers areindicated as A', B' and C' corresponding to recording papers A, B and Cor Example 11.

                  TABLE 16                                                        ______________________________________                                                       Optical density                                                                             Irra-                                                                 Irra-   diation                                          Rec-                 diation time                                             ording               time    (12   O.D. (12 hrs)/                             paper Antioxidant    (0 hr)  hrs)  O.D. (0 hr)                                ______________________________________                                        A'    nil            0.93    0.41  0.44                                       "     hydroquinone   0.95    0.95  1.00                                       "     hydroquinon dimethyl                                                                         0.97    0.70  0.72                                             ether                                                                   "     butylhydroxyanisole                                                                          0.93    0.82  0.88                                       "     p-tert-butylphenol                                                                           0.97    0.65  0.67                                       "     p-tert-butylcatechol                                                                         0.97    0.97  1.00                                       "     2,6-di-tert-butyl-                                                                           1.00    0.98  0.98                                             phenol                                                                  "     2,6-tert-butyl-p-                                                                            0.99    0.57  0.57                                             cresol                                                                  "     methylhydroquinone                                                                           0.92    0.85  0.92                                       "     2,2'-azobis-   0.87    0.53  0.61                                             isobutyronitrile                                                        "     benzotriazole  0.94    0.43  0.46                                       "     diphenylamine  0.94    0.73  0.78                                       "     1,1-diphenyl-2-                                                                              1.01    0.84  0.83                                             picrylhydrazine                                                         "     pyrogallol     0.94    0.84  0.89                                       B'    nil            0.97    0.42  0.43                                       "     hydroquinone   0.99    0.97  0.98                                       "     hydroquinone   1.00    0.69  0.69                                             dimethyl ether                                                          "     butylhydroxyanisole                                                                          0.99    0.84  0.85                                       B'    p-tert-butylphenol                                                                           1.04    0.75  0.72                                       "     p-tert-        1.07    1.03  0.96                                             butylcatechol                                                           "     2,6-di-tert-   1.05    1.03  0.98                                             butylphenol                                                             "     2,6-di-tert-butyl-                                                                           1.06    0.66  0.62                                             p-cresol                                                                "     methylhydroquinone                                                                           0.98    0.95  0.97                                       "     2,2'-azobis-   0.89    0.64  0.72                                             isobutyronitrile                                                        "     benzotriazole  1.03    0.49  0.48                                       "     diphenylamine  1.01    0.81  0.80                                       "     1,1-diphenyl-2-                                                                              1.09    0.93  0.85                                             picryl-hydrazine                                                        "     pyrogallol     1.00    0.91  0.91                                       C'    nil            0.88    0.35  0.40                                       "     hydroquinone   0.92    0.90  0.98                                       "     hydroquinone   0.96    0.69  0.72                                             dimethyl ether                                                          "     butylhydroxyanizole                                                                          0.91    0.80  0.88                                       "     p-tert-butylphenol                                                                           0.95    0.60  0.63                                       "     p-tert butylcatechol                                                                         0.90    0.89  0.99                                       "     2,6-di-tert-   0.97    0.95  0.98                                             butylphenol                                                             C'    2,6-di-tert-butyl-                                                                           0.97    0.47  0.48                                             p-cresol                                                                "     methylhydroquinone                                                                           0.90    0.75  0.83                                       "     2,2'-azobis-   0.81    0.43  0.53                                             isotutyronitrile                                                        "     benzotriazole  0.91    0.38  0.42                                       "     diphenylamine  0.88    0.50  0.57                                       "     1,1-diphenyl-2-                                                                              0.97    0.76  0.78                                             picrylhydrazine                                                         "     pyrogallol     0.91    0.81  0.89                                       ______________________________________                                    

These results reveal that the addition of antioxidants can remarkablyimprove the light resistance. The degree of the improvement more or lessdepends on the type of antioxidant and hydroquinone,p-tert-butylcatechol, 2,6-di-tert-butylphenol and methylhydroquinone areparticularly excellent in improving the light resistance.

Aside from those mentioned above, there are usable styrenated phenol,2,2'-methylenebis(4-ethyl-6-t-butylphenol),4,4'-butylidenebis(3-methyl-6-t-butylphenol),4,4'-thiobis(3-methyl-6-t-butylphenol),2,2'-thiobis(4-methyl-6-t-butylphenol), alkylthiodi propionates,2-mercaptobenzoimidazole, N-n-butyl-p-aminophenol, phenylenediamines,α-naphtylamine, N-phenyl-α-naphthylamine,N,N'-disalicylidene-1,2-propylenediamine, phenothiazine,tris(nonylphenyl)phosphite, triphenylphosphite,tris(3,5-di-t-butyl-4,4-hydroxyphenylphophate, dithiocarbamate,anthogenate, dihydrquinoline derivatives, mercaptobenzimidazoles,monoisopropyl citrate, ethyl protocathecuate, alkyl gallates,nordihydroguaiaretic acid, L-sorbic acid, and the like.

EXAMPLE 16

Various links composed of 77 to 79 wt% of water, 20% by weight ofethylene glycol and 1 to 3% by weight of different types of dyes weremade and applied on a recording paper D' which was made by incorporating0.5 g/m² of methylhydroquinone in the recording paper A'. The lightresistance was measured in the same manner as in Example 15. The resultsare shown in Table 17 below.

                  TABLE 17                                                        ______________________________________                                                  Optical Density (O.D.)                                              Rec-            Irradiation                                                                             Irradiation                                         ording          time      time    O.D. (12 hrs)/                              paper Dye       (0 hr)    (12 hrs)                                                                              O.D. (0 hr)                                 ______________________________________                                        D'    C.I. Basic                                                                              0.95      0.90    0.95                                              Violet 14                                                               A'    C.I. Basic                                                                              0.97      0.37    0.38                                              Violet 14                                                               D'    C.I. Basic                                                                              0.79      0.73    0.92                                              Blue 3                                                                  A'    C.I. Basic                                                                              0.79      0.46    0.58                                              Blue 3                                                                  D'    C.I. Basic                                                                              0.53      0.51    0.97                                              Yellow 11                                                               A'    C.I. Basic                                                                              0.57      0.39    0.69                                              Yellow 11                                                               D'    C.I. Basic                                                                              0.78      0.69    0.89                                              Red 1                                                                   A'    C.I. Basic                                                                              0.79      0.35    0.44                                              Red 1                                                                   D'    C.I. Basic                                                                              0.77      0.75    0.97                                              Red 13                                                                  A'    C.I. Basic                                                                              0.78      0.56    0.72                                              Red 13                                                                  D'    C.I. Acid 0.57      0.52    0.92                                              Yellow 17                                                               A'    C.I. Acid 0.51      0.21    0.81                                              Yellow 17                                                               D'    C.I. Acid 0.61      0.47    0.77                                              Orange 7                                                                A'    C.I. Acid 0.63      0.43    0.69                                              Orange 7                                                                D'    C.I. Acid 0.82      0.57    0.70                                              Red 88                                                                  A'    C.I. Acid 0.80      0.38    0.47                                              Red 88                                                                  ______________________________________                                    

From the above results, it will be seen that though an influence of theantioxidants on the light resistance varies depending on the type ofdye, good results are obtained in all the cases. Accordingly, theaddition of antioxidant is believed effective in improving the lightresistance by application to various types of dye.

The amount of the antioxidants also varies depending on the type but isgenerally in the range of 0.1 to 10% by weight of the coatingcomposition when such composition is applied by the surface coatingtechnique. Larger amounts give an adverse effect on the recordingcharacteristics.

The antioxidants can also be applied by dipping paper in solutions ofantioxidants or internally incorporated paper. This is particularlydescribed in examples which follow.

EXAMPLE 17

A commercially available high quality paper showing a relatively highdegree of water absorptivity was used and an ink jet recording using anink of C.I. Basic Violet 10 was conducted on such paper. The recordedpaper was then dipped an acetone solution of each of antioxidants (2wt%) for 2 seconds. After drying, the light resistance of the dippedpaper was measured using the xeon fade meter. The results are shown inTable 18 below.

                  TABLE 18                                                        ______________________________________                                                    Optical Density (O.D.)                                                                               O.D.                                                     Irradiation                                                                              Irradiation                                                                             (12 hrs)/                                                time       time      O.D.                                       Antioxidant   (0 hour)   (12 hours)                                                                              (0 hr)                                     ______________________________________                                        nil           0.91       0.38      0.42                                       hydroquinone  0.91       0.89      0.98                                       p-tert-butylcatechol                                                                        0.93       0.92      0.99                                       2,2-di-tert-butylphenol                                                                     0.93       0.90      0.97                                       methylhydroqinone                                                                           0.88       0.86      0.98                                       butylhydroxyanisole                                                                         0.88       0.83      0.94                                       diphenylamine 0.90       0.79      0.88                                       pyrogallol    0.89       0.80      0.90                                       ______________________________________                                    

As will be seen from the above results, the dipping method is alsoeffective in improving the light resistance similarly to the surfacecoating method.

EXAMPLE 18

LBKP having a freeness (C.S.F) of 400 ml was used as starting pulp towhich were added 10 wt% of talc, 2 wt% of a wet strength improver and0.5 wt% of antioxidants each based on the solid component of pulp. Thethus added pulps were each used to make papers with a basis weight of 50g/m² in a usual manner.

Then, an ink with the same composition as used in Example 17 was usedand applied on the thus made papers, followed by measuring the lightresistance. The results are shown in Table 19 below.

                  TABLE 19                                                        ______________________________________                                                    Optical Density (O.D.)                                                                               O.D.                                                     Irradiation                                                                              Irradiation                                                                             (12 hrs)/                                                time       time      O.D.                                       Antioxidant   (0 hour)   (12 hours)                                                                              (0 hr)                                     ______________________________________                                        nil           0.85       0.38      0.45                                       hydroquinone  0.86       0.81      0.94                                       p-tert-butylcatechol                                                                        0.89       0.83      0.93                                       2,6-di-tert-butylphenol                                                                     0.90       0.83      0.92                                       methylhydroquinone                                                                          0.85       0.80      0.94                                       butylhydroxyanisole                                                                         0.84       0.79      0.94                                       diphenylamine 0.88       0.75      0.85                                       pyrogallol    0.83       0.79      0.95                                       ______________________________________                                    

Thus, the incorporation of the antioxidants in paper is also effectivein improving the light resistance.

EXAMPLE 19

Example 11 was repeated using various UV absorbers, with the resultsshown in Table 20 below, in which the three recording papers areindicated as A", B" and C" corresponding to recording papers A, B and Cof Example 11.

                  TABLE 20                                                        ______________________________________                                                       Optical Density (O.D.)                                                                      Irra-                                                                 Irra-   diation                                          Rec-                 diation time                                             ording               time    (12   O.D. (12 hrs)/                             paper UV absorber    (0 hr)  hrs)  O.D. (0 hr)                                ______________________________________                                        A"    nil            0.93    0.41  0.44                                       "     2-hydroxy 4-   1.00    0.79  0.79                                             octoxybenzophenone                                                      "     2-hydroxy-4-   0.96    0.83  0.86                                             methoxybenzo-                                                                 phenone                                                                 "     phenylsalicylate                                                                             0.91    0.70  0.77                                       "     p-t-butylphenyl                                                                              0.92    0.77  0.83                                             salicylate                                                              B"    nil            0.97    0.42  0.43                                       "     2-hydroxy-4-   1.02    0.83  0.81                                             octoxybenzo-                                                                  phenone                                                                 "     2-hydroxy-4-   0.98    0.82  0.84                                             methoxy-                                                                      benzophenone                                                            "     phenyl salicylate                                                                            0.94    0.71  0.76                                       "     p-t-butylphenyl                                                                              0.93    0.74  0.80                                             salicylate                                                              C"    nil            0.88    0.35  0.40                                       "     2-hydroxy-4-   0.98    0.85  0.87                                             octoxy-                                                                       benzophenone                                                            C"    2-hydroxy-4-   0.91    0.76  0.84                                             methoxy-                                                                      benzophenone                                                            "     phenyl salicylate                                                                            0.89    0.67  0.75                                       "     p-t-butylphenyl                                                                              0.90    0.69  0.77                                             salicylate                                                              ______________________________________                                    

These results show that the addition of the UV absorbers is effective inimproving the light resistance.

EXAMPLE 20

Various inks composed of 7 to 79 wt% of water, 20 wt% of ethylene glycoland 1 to 3 wt% of various dyes were made and applied on a recordingpaper D' which was made by incorporating 0.5 g/m² of2-hydroxy-4-octoxybenzophenone as UV absorber in the coating layer ofthe recording paper A". The light resistance was measured in the samemanner as in Example 19. The results are shown in Table 21 below.

                  TABLE 21                                                        ______________________________________                                                  Optical Density (O.D.)                                              Rec-            Irradiation                                                                             Irradiation                                         ording          time      time    O.D. (12 hrs)/                              paper Dye       (0 hr)    (12 hrs)                                                                              O.D. (0 hr)                                 ______________________________________                                        A"    C.I. Basic                                                                              0.97      0.37    0.38                                              Violet 14                                                               D"    C.I. Basic                                                                              0.99      0.81    0.82                                              Violet 14                                                               A"    C.I. Basic                                                                              0.79      0.46    0.58                                              Blue 3                                                                  D"    C.I. Basic                                                                              0.83      0.75    0.90                                              Blue 3                                                                  A"    C.I. Basic                                                                              0.57      0.39    0.69                                              Yellow 11                                                               D"    C.I. Basic                                                                              0.59      0.51    0.86                                              Yellow 11                                                               A"    C.I. Basic                                                                              0.79      0.35    0.44                                              Red 1                                                                   D"    C.I. Basic                                                                              0.81      0.70    0.86                                              Red 1                                                                   A"    C.I. Basic                                                                              0.78      0.56    0.72                                              Red 13                                                                  D"    C.I. Basic                                                                              0.77      0.68    0.88                                              Red 13                                                                  A"    C.I. Basic                                                                              0.51      0.21    0.41                                              Yellow 17                                                               D"    C.I. Basic                                                                              0.54      0.41    0.76                                              Yellow 17                                                               A"    C.I. Acid 0.63      0.43    0.69                                              Orange 7                                                                D"    C.I. Acid 0.63      0.58    0.92                                              Orange 7                                                                A"    C.I. Acid 0.80      0.38    0.47                                              Red 88                                                                  D"    C.I. Acid 0.77      0.69    0.90                                              Red 88                                                                  A"    C.I. Acid 0.92      0.32    0.35                                              Violet 49                                                               D"    C.I. Acid 0.91      0.85    0.93                                              Violet 49                                                               A"    C.I. Acid 0.81      0.72    0.88                                              Blue 7                                                                  D"    C.I. Acid 0.85      0.78    0.92                                              Blue 7                                                                  A"    C.I. Acid 1.00      0.83    0.83                                              Black 2                                                                 D"    C.I. Acid 1.05      1.04    0.99                                              Black 2                                                                 A"    C.I. Acid 0.94      0.86    0.91                                              Black 31                                                                D"    C.I. Acid 0.95      0.91    0.96                                              Black 31                                                                A"    C.I. Direct                                                                             0.48      0.34    0.71                                              Yellow 50                                                               D"    C.I. Direct                                                                             0.49      0.43    0.88                                              Yellow 50                                                               A"    C.I. Direct                                                                             0.71      0.47    0.66                                              Red 80                                                                  D"    C.I. Direct                                                                             0.70      0.60    0.86                                              Red 80                                                                  ______________________________________                                    

The influence of the benzophenone on the light resistance more or lessdepends on the type of UV absorber but good results are obtained in allcases.

When the UV absorbers are applied by the surface coating technique, theyare generally used in an amount of 0.1 to 10 wt% of the coatingcomposition of binder and filler. Similarly to the antioxidants andcompounds capable of reacting with dye, larger amounts give an adverseeffect on the recording characteristics.

EXAMPLE 21

A commercially available high quality paper showing a relatively highdegree of water absorptivity was used and an ink jet recording using anink of C.I. Basic Violet 10 was conducted on such paper. The recordedpaper was then dipped in an acetone solution of each of UV absorbers (2wt%) and dried, after which it was subjected to the measurement of lightresistance. The results are shown in Table 22 below.

                  TABLE 22                                                        ______________________________________                                                    Optical Density (O.D.)                                                          Irradiation                                                                             Irradiation                                                                             O.D.                                                      time      time      (12 hrs)/                                   UV absorber   (0 hr)    (12 hrs)  O.D. (0 hr)                                 ______________________________________                                        nil           0.90      0.38      0.42                                        2-hydroxy-4-octoxy-                                                                         0.93      0.71      0.76                                        benzophenone                                                                  2-hydroxy-4-methoxy                                                                         0.91      0.77      0.85                                        benzophenone                                                                  phenyl salicylate                                                                           0.89      0.68      0.76                                        p-t-butylphenyl                                                                             0.90      0.59      0.66                                        salicylate                                                                    ______________________________________                                    

As will be clear from the above results, the dipping method is effectivein improving the light resistance.

EXAMPLE 22

LBKP having a freeness (C.S.F) of 400 ml was used as starting pulp towhich were added 10 wt% of talc, 2 wt% of a wet strength improver and0.5 wt% of UV absorbers each based on the solid component of pulp. Thethus added pulp were used to make papers with a basis weight of 50 g/m²in a usual manner.

Then an ink with the same composition as used in Example 21 was used andapplied on the thus made papers, followed by measuring the lightresistance. The results are shown in Table below.

                  TABLE 22                                                        ______________________________________                                                    Optical Density (O.D.)                                                                               O.D.                                                     Irradiation                                                                              Irradiation                                                                             (12 hrs)/                                                time       time      O.D.                                       UV absorber   (0 hr)     (12 hrs)  (0 hr)                                     ______________________________________                                        nil           0.82       0.39      0.47                                       2-hydroxy-4-octoxy-                                                                         0.88       0.63      0.72                                       benzophenone                                                                  2-hydroxy-4-methoxy-                                                                        0.85       0.67      0.79                                       benzophenone                                                                  phenyl salicylate                                                                           0.85       0.58      0.68                                       p-t-butylphenyl                                                                             0.81       0.51      0.63                                       salicylate                                                                    ______________________________________                                    

The UV absorbers can be effectively utilized even by the internalapplication method as will be apparently seen from the above results.

What is claimed is:
 1. A recording sheet for ink jet recording made froma composition comprising a mixture of 100 parts by weight of a stockpulp, 10 to 60 parts by weight of a white filler, and 2 to 20 parts byweight of a binder resin selected from the group consisting ofpolyvinylpyrrolidone, vinylpyrrolidone-vinyl acetate copolymer and amixture thereof.
 2. A recording sheet according to claim 1, wherein saidbinder is polyvinylpyrrolidone.
 3. A recording sheet according to claim1, wherein said binder is vinylpyrrolidone-vinyl acetate copolymer.
 4. Arecording sheet according to claim 1, wherein said white filler is clay,talc, calcium carbonate, calcium sulfate, calcium silicate, diatomaceousearth, magnesium silicate, terra abla, activated clay, magnesium oxide,magnesium carbonate or aluminium hydroxide in the form of a powder.
 5. Arecording sheet according to claim 1, further comprising a binder resinused in combination with the first-mentioned binder resin, saidfirst-mentioned binder resin being used in an amount of at least 20 wt%of the combination when the second-mentioned binder resin shows waterabsorptivity or in an amount of at least 33 wt% of the combination whensaid second mentioned binder resin shows little water absorptivity.
 6. Arecording sheet according to claim 1, further comprising a plasticizerto control the hardness of a film formed from the binder resin.
 7. Arecording sheet according to claim 1, further comprising an aqueousemulsion type resin or an alcohol-soluble resin, which shows a waterproof property when dried in the form of a film, in an amount of 1 to 50wt% of a combination with the binder resin, whereby the resultingcoating is imparted with water proof.